Ruling 1447
A follower must not say takbīrat al‑iḥrām before the imam. In fact, the recommended precaution is that he should not say takbīrat al‑iḥrām until the imam has completed saying it.
Prayer: Saying Takbirat al-Ihram Before the Imam
Practical Laws of Islam as per the teachings of Ayatullah Sistani
